It appears to me that most of the URL submissions are just tech blog websites using HN as a tool to drive traffic. There are even users out there that just wait for a new blog post by jacquesm so that they can post it for free karma. I think in situations like this, karma and voting become less useful because people will up vote just so that something might land on the front page, for traffic.
This leads me to another trend I see a ton in #startups. Somebody will create a new submission and link it on IRC and ask for free up votes so that it gets more visibility. Once again, this is where up votes aren't being used properly. But, I also think it highlights a potential difficulty for valuable new submissions - it's difficult to get that initial visibility and up votes. Perhaps to remedy this, make the "/newest" section be the default section, and move the highest voted to something that you have to navigate to. This will at least highlight new entries for people just hitting the main URL.